Missing wireless sensor

[Keith Belt]

Using a few 2-way wireless sensors on a mostly hardwired system.  Been fine for a month or two, but got a fault message on one of them, with the system saying its “missing”.  I’m not sure how to interpret that or why it would report that way.  I cycled power on it by momentarily removing the battery, but still reports “missing”.  Not sure how to “find” it.

[Michael Burrell]

In alarm systems, the wireless transmitters are supervised. This means the system is aware if something happens to one of the wireless sensors. The supervision is handled by the wireless sensor “checking in” with the receiver once every hour.

If a burglar device fails to check in for 24 hours, it will go “missing.” This means the system has not heard any signals from that sensor in 24 hours. It should receive a check-in every hour, but it only needs to receive one check-in within the 24-hour period to avoid being considered missing.

If a fire/CO detector fails to check in for 4 hours, it will go “missing.” Life safety regulations require a shorter supervisory failure window, so it will be marked as missing after failing to check in for four hours straight.

There are a few reasons a device might go “missing”:

1. The device could have an issue and not be communicating with the receiver. Please reference the ID of the missing device and test it to see if it is transmitting.
2. There could be an inactive wireless transmitter ID in the wireless setup. This can happen if a transmitter ID is manually entered but doesn’t physically exist in the system.
3. You might have a setting enabled under “System Settings” called “RF Trouble On Power-Up.” This will indicate a missing trouble condition for all wireless sensors if the system is power cycled. For UL-listed installations, it is required that an “unknown” state of a wireless sensor be shown as a trouble condition. When the system is power cycled, it cannot know the state or status of the wireless sensors until they communicate with the receiver. If you use this option, you must activate each wireless device after a power cycle to clear the missing trouble condition. If the option is off, the system assumes all wireless sensors are good for the first hour after power-up or until they check in. When they check in, the system will then have their status and state.

Additionally, it is possible to disable the “Enable On Board Receiver” option in the system settings, which, depending on the configuration of the system, could also cause this issue.

If your having this issue with a specific wireless device, please test that device to see if it is providing a change of state on the keypad. If viewing it from the app, see if you are getting a signal strength indication on the unit. If this is an ELK two way wireless device it will have a LED that will lite up green or red when it transmits. If it is red this indicates it is not talking to the receiver. Green indicates it got good acknowledgement.

 

 

 

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